DE2412712B2 - Process for the production of methacrylic acid - Google Patents

Description

The invention relates to a process for the production of methacrylic acid by converting methacrolein with molecular oxygen in the vapor phase at a temperature of 250-450 ° C in the presence of Steam and in the presence of an oxide catalyst containing molybdenum, phosphorus and antimony.

Such a method is known from DE-AS 12 45 363. However, it is not for industrial manufacture of methacrylic acid from methacrolein, since the yields are extremely low. There is a reason for this in that methacrolein decomposes easily. When it decomposes, it decomposes with complete oxidation into Carbon monoxide and / or carbon dioxide. In addition, methacrolein is easily polymerizable. Further conventional also inadequate catalysts are disclosed in US Pat. Nos. 3,358,020 and 34 35 069 and DE-Offenlegungsschriften 22 52 037 and 22 20 799. These catalysts are suitable good for making. However, they show only very poor results in the production of methacrylic acid.

It is thus the object of the present invention to provide a process for the preparation of methacrylic acid by oxidizing methacrolein with the help of molecular oxygen to create, which with high Yield and high selectivity leads to the desired product.

This object is achieved according to the invention by a process for the production of methacrylic acid by reacting methacrolein with molecular oxygen in the vapor phase at a temperature of 250-45O ° C. in the presence of steam and in the presence of a molybdenum. Oxide catalyst containing phosphorus and antimony dissolved, where X is at least one of the elements tungsten, barium, chromium, lead, niobium, tantalum, tin, nickel, iron or zirconium and δ corresponds to the oxidation level of the elements, or the general formula II

where X and δ correspond to the above definition and Y is at least one of the elements strontium, titanium, germanium, cerium or silver is used.

With the method according to the invention, oxidative side reactions are suppressed to a minimum or completely eliminated, and furthermore, the polymerization reaction is also suppressed. With the inven-

: » The process according to the invention achieves a conversion of methacrolein to meihycralic acid or a selectivity in the range of 60 -90 or 79 -85.

Preferred catalysts have the following composition:

Md ₁₂ P,, Sb ,,.;, JX, _S O ,,

where ό corresponds to the oxidation state of Mo, P, Sb and X. When each of these elements is in a highly oxidized state, δ preferably denotes 36-87. Catalysts in which X is, W, Ba, Fe, Zr or Cr or combinations of these elements show superior properties.

Further preferred catalysts have the following composition:

where δ corresponds to the oxidation state of Mo, P, Sb, X and Y If the components are in a highly oxidized state, δ is in the range from 44 to 108.

In a preferred group of catalysts, X is at least one of the elements W, Ba, Cr, Pb and Y is at least one of the elements Sr, Nb, Ta ₁ Ce, Fe ₁ Zr and Ni. In a further preferred group of catalysts, X is at least one of the elements Nb, Ta, Sn and Ni and Y is at least one of the elements Zr, Sr and Ti. In a further preferred group of catalysts, X is at least one of the elements Fe and Zr and Y at least one of the elements Ge, Ce, Ag and Ti.

The catalyst according to the invention can be prepared in various ways. The catalyst is preferably prepared by concentrating a solution or a suspension with the desired components and drying the concentrate obtained. In this case, the dried product at a temperature of 150 to 500 ° C and preferably at 200 to 420 ⁰ C is calcinicrt for about 1 to about 48 hours in air. The calcined product is then ground to a size of 35 to 100 meshes / 2.5 cm. Then it is ready for use. The catalyst prepared in this way has a specific surface area of 0.1 to 50 m ² / g.

The exact chemical composition of the catalyst according to the invention is not fully known. It can be assumed, however, that it is a homogeneous or uniform mixture of the Oxides of the components is or is a

Compound or a complex compound through the reaction of phosphomolybdate and the oxides of the other components.

In particular, catalysts containing antimony molybdate have particularly good properties. In In some cases the catalyst can improve the physical properties of a support material be applied, such as. B. silica, silica containing Materials, silicon carbide, aluminum oxide or the like. The content of carrier material is preferably in the range from 30 to 97 percent by weight based on the catalyst. The following are a few the possible starting materials for the production of the catalyst are listed:

Possible sources of molybdenum are: ortho-, meta- or paramolybdic acid, ortho-, meta- or Paramolybdates, heteropolymolybdic acid, heteropolymolybdates or molybdenum oxide.

Suitable sources of phosphorus are:

Phosphoric acid, phosphates, polyphosphoric acid, polyphosphates or the like. Phosphomolybdic acid is also used or Phosphormoiybdate as sources for molybdenum and phosphorus in question.

Suitable sources of antimony are:

Antimony chloride, antimony oxide or antimony sulfate.

Suitable tungsten sources are:

Tungsten trioxide, tungstic acid or tungstates.

Suitable sources of barium are:

Barium oxide or barium nitrate.

Suitable sources are:

Chromium oxide, chromium nitrate or chromium sulfate.

Suitable sources of lead are:
Lead oxide or lead nitrate.

Suitable sources of niobium:

Niobium oxide, niobium hydroxide or niobium nitrate.

Suitable sources of tantalum are:
Tantalum pentoxide.

Suitable sources of tin are:
Tin oxide or tin chloride.

Suitable nickel sources are:

Nickel nitrate or nickel chloride.

Suitable sources of iron are:

Iron oxide, iron nitrate or ferric chloride.

Suitable sources of zircon are:

Zirconium oxide or zirconium nitrate.

Suitable sources of strontium are:

Strontium Oxide or Strontium Nitrate.

Suitable titanium sources are:

Titanium tetrachloride or titanium oxide.

Suitable sources of germanium are:

Germanium oxide or germanium tetrachloride.
Suitable cerium sources are:

Cerium oxide or cerium nitrate
Suitable sources of silver are:

Silver oxide or silver nitrate

The oxygen can either be in pure form or

are supplied diluted with an inert gas, further

κι can also be enriched with oxygen or air

normal air can be used. Because of

Air is particularly preferred for economy.

The reaction according to the invention can be carried out either in the

Pest bed or carried out in the catalyst fluidized bed

ι> been. The reaction temperature is in the range of

230 to 450 ⁰ C and preferably in the range from 250 to

280 ⁰ C. The reaction pressure can be in a wide range

vary and in particular in the range from 0.5 to

40.5 bar and preferably in the range from about 1 to 10

-'" bar. If the reaction pressure is relatively high, so can

the reaction temperature can be lowered somewhat. the

Contact time usually varies in the range of 0.2 to

30 s and preferably in the range of 1 to 20 s

Molar ratio of oxygen to methacrolein im

r> supplied gas is usually in the range of

1: 10-10: 1 and preferably in the range of

1: 3-3: l.

Steam is added to the gaseous reaction mixture. This improves the yield. In addition, the gaseous mixture of the reactants with nitrogen, saturated hydrocarbons, such as methane, propane, butane or the like. Or with another inert gas. The concentration the steam can range from 20 to 80 r. Vol .-% vary and preferably in the range of 10 up to 50% by volume, based on the gas introduced.

Since the present reaction is exothermic, the temperature of the reaction vessel must be controlled to keep the reaction under control to μ. Thus, the reaction vessel is preferably heated in a metal or molten salt bath, or in a solid-state fluidized bath.

The methacrylic acid can be isolated from the reaction products by various methods. i> Suitable methods include condensation and / or extraction followed by distillation.

To calculate the conversion of methacrolein and the selectivity and the yield of methacrylic acid the following formulas are used. ■> "The analysis values refer to the values of gas chromatography.

Conversion of methacrolein in the introduced gas (mol) Methacrolein in the exhaust gas (mol)

(Pro / enl)

Methacrolein im / !! led (ias (mol)

HH)

Selectivity methacrylic acid in exhaust gas (mol)

(Iro / enl) Methacrolein im / ugcfiihrtcn (his (Mol) Methacrolein in the exhaust gas (Mol)

UH)

selectivity
(l-ssigsaure)
(l'ro / cnl)

Acetic acid in exhaust gas (mol)
Methacrolein in the (Jas (mol) methacrolein in exhaust gas (mol)

In the following, the invention is explained in more detail with the aid of exemplary embodiments.

example 1

A solution of 5.7 g of antimony trichloride is dissolved in 100 cm ^{3 of} 6 η HCl and this solution, with stirring, becomes a solution of 58 g of phosphomolybdic acid

(P ₂ O ₅ · 24 MoO ₃ ■ 48 H ₂ O)

dissolved in 150 cm ^j water. 5.8 g of powdery tungsten trioxide are added to the resulting solution, and the mixture is heated with stirring and concentrated to obtain a cake. The cake is dried at 120 ⁰ C for 12 hours and the dried product is calcined for 12 hours at 380 ° C, obtaining a solid with the following empirical composition:

Sb ₁ Mo ₁₂ W ₁ P ₁ O ₄ L ₅

This solid is passed through a sieve to obtain catalyst particles with a size of 35 to 100 mesh / 2.5 cm. A U-shaped reaction vessel with an internal diameter of 8 mm is filled with 4 ml of the catalyst. This reaction vessel is placed in a bath of molten salt at a temperature of 32O ⁰ C. The gaseous reactant mixture of 55% nitrogen, 30% steam, 10% oxygen and 5% methacrolein (percent by volume) is passed through the reactor, with a contact time of 2 seconds. is elected The following results are obtained:

Methacrolein conversion 89%

Selectivity with regard to

Methacrylic acid 72%

Selectivity with regard to

Acetic acid 11.0%.

Examples 2 to 10

Catalysts are prepared in the same way as in Example 1, except that 3.8 g of barium oxide, 5.6 g of lead oxide or 1.9 g of chromium oxide are used instead of tungsten trioxide. One then obtains the atomic ratio few N ^? The catalysts obtained in this way are used for the oxidation of methacrolein under essentially the same conditions as in Example 1. The results are shown in Table 1.

Table 1 Catalysts Melhacrolein Methacrylic acid acetic acid example conversion selectivity selectivity No. Sb ₁ MOi ₂ Ba ₁ P ₁ O ₃₉₅ 89 69 12th 2 Sb ₁ MOi ₂ PbIP ₁ O ₃₉₅ 85 53 11 3 SbIMOi ₂ Cr ₁ PiO ₄₀ 90 74 U 4th Sb ₁ Mo ₁₂ W ₁ Ba ₁ PiO ₄₁₅ 70 88 7th 5 Sb | Mo, ₂ W, Cr, PiO ₄₃ 90 70 12th 6th SbIMOi ₂ W ₁ PbIP ₁ O ₄₂₅ 78 67 9 7th SbIMOi ₂ BaIPb ₁ P ₁ O ₄₀₅ 75 65 14th 8th Sb | Mo ₁₂ Ba, Cr | P | O ₄ | 74 69 8th 9 Sb | Mo ₁₂ Cr, Pb | P | O ₄₁ 85 55 7th 10

Comparative cispicle 1 to 6

Similar to Examples 1 to 10 catalysts are prepared which the Atomverhallnissc acc. Table 2 have. The reaction of Example I is repeated with these catalysts. The results are compiled in Table 2:

Table 2 catalyst Methacrolein Methacrylic acid acetic acid comparison conversion selectivity selectivity No. Sb | Mo, ₂ P | O ₃₈₅ 90 23 26th 1 Sb, MOi ₂ WiO ₄₀₅ 40 20th 11 2 Sb, Mo | ₂ Ba | O ₃₈₅ 33 17th 6th 3 Sb | MO | ₂ Sn, O _W5 35 26th 7th 4th M () | ₂ Zr, P | O ₄₀₅ 28 24 14th S. Mon ₁₂ P ₁ O ₃ M 64 31 5 6th

example

A solution of 5.7 g of antimony trichloride in 100 cm ^{1 of} η HCl is stirred into a solution of 58 g of phosphomolybdic acid

(P ₂ O ₅ · 24 MoOi ■ 48 H ₂ O)

given in 150 cm 'of water. 5.8 g of powdered tungsten trioxide are added to the resulting solution and then 3.3 g of niobium pentoxide are added. The mixture is heated with stirring and concentrated to obtain a cake. The cake is dried at 120 ⁰ C for 12 hours and the dried product is calcined at 400 ° C for hours to give a solids content of the following empirical formula:

Sb, Mo ₁₂ W, Nb, P, А44

The solid is passed through a sieve, whereby catalyst particles with a particle size of up to 100 mesh / 2.5 cm are obtained. A U-shaped one The reaction vessel with an internal diameter of 8 mm is filled with 4 ml of the catalyst. The catalyst is used for the oxidation of methacrolein, with essentially the same conditions as in Example 1 can be used. The following results are obtained:

Conversion of methacrolein 87%

Selectivity with regard to

Methacrylic acid 65%

Selectivity with regard to

Acetic acid 12%.

Examples 12 to 35

In a manner similar to Example 11, catalysts are prepared, with 3.8 g of barium oxide. 5.6 g Lead oxide or 1.9 g chromium oxide are used instead of tungsten oxide and 2.6 g strontium oxide, 4.3 g cerium oxide, 4.1 g iron oxide. 1.1 g of zirconium oxide or 1.9 g of nickel oxide are used instead of the nitrous oxide will. This gives an empirical formula according to Table 3. The reaction according to Example 1 is carried out with the obtained catalysts repeatedly. The results obtained are summarized in Table 3:

Tabel

Example no.

12 13

14 15 16

18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

Catalysts Methacrolein Solohacrylic acid acetic acid conversion selectivity selectivity (%> (%) Co) Sb ₁ Mo ₁₂ W ₁ Sr ₁ P ₁ O ₄ ,, 89 64 9 Sb ₁ MOuW ₁ Ce ₁ PiO ₄ ,, 88 50 12th Sb ₁ Mo ₁ JW ₁ Ie ₁ P ₁ O ₄₄ 82 59 11 Sb ₁ Mo ₁₂ W ₁ Zr ₁ P ₁ O ₄ ,, 87 55 10 Sb ₁ Mo ₁₂ W ₁ Ni ₁ P ₁ O ₄₂ , 83 57 8th SbIMo ₁₂ Ba ₁ TaIPiO ₄ : 83 62 V SbIMo ₁₂ BaISr ₁ P ₁ O ₄₀₅ 80 60 12th SbIMOi ₂ Ba ₁ CeIP ₁ O ₄ ,, 85 63 8th Sb | MouBa, Fe | P, O ₄ |, 82 61 9 Sb ₁ Mo ₁₂ Ba ₁ ZrIPiO ₄ I, 75 67 -7 Sb ₁ Mo ₁₂ Ba ₁ Ni ₁ PiO ₄₀ , 72 62 6th Sb ₁ Mo ₁₂ Pb ₁ Nb ₁ PiO ₄₂ 94 59 14th Sb ₁ Mo ₁₂ Pb ₁ Sr ₁ P ₁ O ₄₀ , 75 57 17th Sb ₁ Mo ₁₂ Pb ₁ Ce ₁ P ₁ O ₄₁ , 73 55 14th Sb ₁ Mo ₁₂ Pb, Ie ₁ P ₁ 0 ₄₂ 85 54 12th Sb ₁ MOi ₂ Pb ₁ ZrIP ₁ O. ,, 83 57 11 Sb ₁ Mo ₁₂ PbINi ₁ P ₁ O ₄₁ I ₅ 87 51 11 Sb ₁ Mo ₁₂ Cr ₁ TaIP ₁ O ₄₂₅ 91 57 11 Sb ₁ Mo ₁₂ Cr ₁ Sr ₁ P ₁ O ₄₁ 83 70 13th SbIMo ₁₂ Cr ₁ Ce ₁ P ₁ O ₄₂ 85 55 9 Sb ₁ Mo ₁₂ Cr ₁ Fe ₁ P ₁ O ₄ I ₅ 90 51 7th SbIMo ₁₂ Cr ₁ Zr ₁ P ₁ O ₄₂ 86 52 10 Sb ₁ Mo ₁₂ Cr ₁ Ni ₁ P ₁ O ₄ , 88 64 10

Examples 35 to 48

Catalysts are produced in a similar manner as in Example 1, the atomic ratios according to the table 4 can be set. The reaction according to Example 1 is repeated using these catalysts. The results according to Table 4 are obtained:

Table 4

IO

Example catalysts

No.

Methacrolein Conversion

Methacrylic acid
selectivity

Acetic acid selectivity

35 Sb ₃ Mo ₁₂ W ₁ P ₁ O ₄₁₅ 90 75 12th 36 Sb ₁ Mo ₁₂ W ₃ P ₁ O ₄₇₅ 93 63 14th 37 Sb ₁ Mo ₁₂ W ₁ P ₃ O ₄₆₅ 50 54 5 38 Sb ₁ Mo ₁₂ W ₁ P ₁ O ₄₇ , 85 71 K) 39 Sb ₆ Mo ₁₂ W ₁ P ₁ O ₄₁ , 89 69 11 40 Sb ₁ Mo ₁₂ W ₆ P ₁ O ,,, 82 65 7th 41 Sb ₁₁ Mo ₁₂ W ₁ P ₁ O ₄₁ , 75 59 5 12th Sb ₉ Mo ₁₂ W ₁₁ P ₁ O ₆ ,, 72 53 6th 43 Sb ₁ Mo ₁₂ W ₁ Ba ₁ P ₁ O ₄₁ ,, 91 71 13th 44 Sb ₁ MO] ₂ WiBa ₁ I ¹ O ₄₂ , So 75 OK 45 Sb ₁ Mo _n W ₁ Ba ₁ P ₁ O ₄₄ , 84 73 <; 46 Sb ₁ Mo ₁₂ W ₁ Ba ₆ P ₁ O ₄₀ , 77 65 7th 47 SbIMOi ₂ W ₆ Ba ₁ P ₁ O ,,,, 70 60 4th 48 Sb ₆ MOpW ₁ BaIP ₁ O ₄₂ , 87 68 11

Example 49

A solution of 5.7 g of antimony trichloride in 100 cm ' 6 ■ HCl is stirred into a solution of 58 g of phosphomolybdic acid

(P> 0 ₅ ■ 24 MoOi ■ 48 H ₂ O)

given in 150 cm ^{1 of} water. 2.0 g of powdery iron oxide (Fe ₃ Oj) is added to the solution. The mixture is heated with stirring and concentrated to obtain a cake. The kitchen is dried at 120 ° C. for 12 hours and the dried product is calcined at 380 ° C. for 12 hours, a solid of the following formula being obtained:

Sb ₁ Mo ₁₂ Fe ₁ PiO ₄ O.

The solid is passed through a sieve to obtain catalyst particles with a particle size of 35 to 100 mesh / 2.5 cm. A U-shaped reaction vessel having an inner diameter of 8 mm is mixed with 4 ml of the catalyst filled The reaction vessel is placed in a molten salt bath and heated to 32O ⁰ C. A gaseous reaction mixture of 55% nitrogen, 30% water vapor. 10% oxygen and 5% methacrolein (volume percent) is sent through the reaction vessel, with a contact time of

Table 5

4 see. is chosen. The following results are obtained:

Methacrolein conversion 93%

Selectivity of methacrylic acid 55%

Acetic acid selectivity 10%.

Example 50

Catalysts are prepared in a manner similar to Example 49, but with zirconium oxide is used instead of iron oxide. A catalyst of the empirical formula is obtained:

The reaction according to Example 49 is repeated with this catalyst, with the following Results are achieved:

Methacrolein conversion 79%

Selectivity to methacrylic acid 62%

Acetic acid selectivity 12%.

Comparative Examples 7-11

In a manner similar to Example 49, catalysts are prepared whose atomic ratios in Table 5 are given. The reaction of Example 49 is repeated with this catalyst, the in Results summarized in Table 5 are obtained:

Comparative example
No.

Catalysts

Methacrolein Conversion

Methacrylic acid selectivity

Acetic acid selectivity

7th SbIMo ₁₂ P ₁ O ₃₈₅ 90 25th 15th 8th Sb ₁ MOi ₂ ZrIO ₃₉₅ 40 20th 5 9 Sb, MO) ₂ Fe, O ₃₉ 46 23 4th 10 ΜουΖΓ, Ρ, Οίο, - 60 31 7th 11 MOi ₂ Fe ₁ P ₁ O ₄₀ 70 40 9

Example 51

A solution of 5.7 g of antimony trichloride in 100 cm ' 6 η HCl is stirred into a solution of 58 g of phosphomolybdic acid (molybdophosphoric acid)

(P ₂ O ₅ · 24 MoO, · 48 H ₂ O)

given in 150 cm 'of water. Powdered iron oxide and zirconium oxide are added to the resulting solution and the mixture is heated with stirring and concentrated to a cake. The cake is dried for 12 hours at 120 ^° C. and the dried product is ^{calcined for 12 hours at 400 °} C. and a solid of the empirical formula is obtained

The solid is passed through a sieve, catalyst particles having a particle size of im Range of 35 to 100 stitches / 2.54 cm is obtained. A U-shaped reaction vessel with an inside diameter of 8 mm is filled with 4 ml of catalyst. This catalyst is used to oxidize methacrolein essentially the same conditions as in Example 1 were used. The following are obtained Results:

Conversion of methacrolein 89%

Selectivity, in terms of

Methacrylic acid 68%

Selectivity with regard to

Acetic acid 8%.

Examples 52 to 59

Catalysts are prepared in a manner similar to Example 51, using germanium oxide, Cerium oxide, silver oxide or titanium oxide with or without iron oxide and zirconium oxide are used, whereby the empirical formulas according to Table 6 can be obtained. The reaction according to Example 49 is carried out using of these catalysts repeatedly. The results shown in Table 6 were obtained.

Table 6

example Catalysts Methacrolein Methacrylic acid Kssgic acid No. conversion
("O) Selectivity Selectivity 52 Sb ₁ MOi ₂ FeIGeIP ₁ O ₁ , 90 61 7th 53 Sb, Mo | ₂ Fe, Ce, P | O ₄₂ 86 70 7th 54 Sb, MO |, Fe, Ag | P | O, | 82 71 Il 55 Sb | MO |, Fe, Ti, PiO ₄₂ 75 65 12th 56 SbIMOi ₂ ZrIGe ₁ PiO ₄ M 71 70 8th 57 Sb | MO | ₂ Zr, Ce | P, O _42i 93 60 15th 58 Sb | Mo |, ZriAg | P | O ₄ |, 90 58 4th 59 Sb, Moi, Zr | Ti | P | O ", 79 62 13th

Example 60

A solution of 5.7 g of antimony chloride in 100 cm '6 η HCl is stirred into a solution of 58 g Molybdophosphoric acid

(P ₂ O ₅ · 24MoO ₁ · 48H ₂ O)

given in 150 cm 'of water. 33 g of niobium pentoxide will be added to the resulting solution. The mixture is heated with stirring and concentrated, leaving a cake is obtained. The cake is at 120 ° C for 12 Hours dried and the dried product is calcined at 400 ° C for 12 hours, wherein one receives a solid of the following empirical formula:

Sb ₁ Mo ₁₂ Nb ₁ PiO ₄ I.

The solid is passed through a sieve to obtain catalyst particles with a particle size in the range from 35 to 100 mesh / 24 cm. A U-shaped reaction vessel with an internal diameter of 8 mm is filled with 4 ml of catalyst. The reaction vessel is placed in a molten salt bath and heated to 320 ⁰ C. A gaseous reaction mixture of 55% nitrogen, 30% steam, 10% oxygen and 5% methacrolein (percent by volume) is passed through the reaction vessel, with a residence time of 2 seconds. is chosen. The following results are obtained:

Conversion of methacrolein 83%

Methacrylic acid selectivity 66%

Acetic acid selectivity 13%.

Examples 61-69

en It are made in a manner similar to Example 60 Catalysts produced, but 5.0 g of tantalum pentoxide, 1.9 g of nickel oxide or 3.8 g of tin oxide or a combination of the same can be used instead of niobium pentoxide. The atomic ratios obtained

b ". are shown together in Table 7. The reaction of the Example 60 is repeated using the same catalyst. The results obtained are compiled in Table 7:

Table 7

Example catalysts

No.

61
62
63

64
65
66
67
68
69

Sb | Mo, 2Nb | Ta | P, (). ,,

Sb ₁ MOi ₂ Nb ₁ Ni ₁ P ₁ O ₄ ,

14th

Methacrolein Methacrylic acid Acetic acid- conversion Selectivity selectivity 67 57 4th 90 74 11 81 69 10 97 54 23 91 57 11 94 58 7th 88 60 9 88 64 IO 85 62 8th

Comparative Examples 12 -

Catalysts are prepared in a manner similar to Examples 64-69, with the atomic ratios according to Table 8 can be obtained. The reaction

Table 8

Comparative example No.

Example 1 is repeated using these catalysts. The results are in Table 8 compiled:

Catalysts

Methacrolein Conversion

Methacrylic acid acetic acid selectivity selectivity

12th
13th
14th
15th
16
17th
18th
19th
20th
21
22nd
23
24
25th

Sb ₁ Mo ₁₂ P ₁ O ₁₈ ,

Sb ₁ TaIP ₁ O ₆₅

Mo ₁₁ Cr ₁ PiO ₄₁ ,

Sb] Mo ₁₁ Ni ₁ O ^ ₅

SbIMo ₁₂ Nb ₁ Ta ₁ O ₄ ;

Mo ₁₂ Nb ₁ Ta ₁ PiO ₄ ,,

Sb ₁ Mo ₁₂ Nb ₁ Sn ₁ O ₄ : SbIMo ₁₂ Nb ₁ Ni ₁ O ₄₁

MOi ₂ Sn ₁ Ta ₁ P ₁ O ₄₂ Mo, ₂ Sn, Ni | P | O ₄₁ ,

90 41 64 58 48 62 59 24 28 33 61 22 65 48 23 25 28 32 35 37 41 25 23 19 35 18 39 36

26th

8 7 9 8 3 4 3 6

1 6

feO

Example 70

A solution of 5.7 g of antimony trichloride in 100 cm ^{3 of} η HCl is stirred into a solution of 58 g of molybdophosphoric acid

(P2O5 24 MoO ₃ 48 H ₂ O)

given in 150 cm ^{3 of} water. 33 g of powdered niobium pentoxide are added to the resulting solution, whereupon 2.0 g of iron oxide are added. The mixture is heated with stirring and concentrated, to obtain a cake This cake is dried at 120 ⁰ C for 12 hours and the Eetrocknete product is calcined at 400 ° C for 12 hours to obtain a solid with the following empirical formula:

The solid is passed through a sieve, where catalyst particles with a particle size of up to 100 mesh / 2.5 is obtained. A U-shaped reaction vessel with an internal diameter of 8 mm is obtained filled with 4 ml of catalyst. The reaction according to Example 60 is carried out using this catalyst repeated. The following results are obtained:

Conversion of methacrolein in terms of selectivity

95%

15 16

Methacrylic acid 58% tin oxide or 5.0 g tantalum oxide instead of the niobium pen

Selectivity in terms of oxyds are used and 3.1 g of strontiumoxy

Acetic acid 12%. or 2.0 g titanium oxide used instead of iron oxide:

will. The empirical formulas of the obtained

B e i s ρ i e 1 e 71 to 79 'catalysts are listed in Table 9 Di.

Reaction according to Example 60 is carried out with this catalyst

Similar to Example 70, catalysts are repeated. The results are in the table
produced, but 1.9 g nickel oxide, 3.8 g put together

Table 9

Example catalysts methacrolein methacrylic acid acetic acid

No conversion selectivity selectivity

71 Sb ₁ Mo ₁₂ Nb ₁ Fe ₁ P ₁ O ₄₂₅ 73 73 8th 72 Sb ₁ Mo ₁₂ Ni ₁ Fe ₁ P ₁ O ₄₁ 92 61 U 73 Sb] Mo ι> Sn ι Fc ι Ρ | Ο.4! 82 70 8th 74 SbiMoιιΧϋιFcιP [O.JI> 73 60 10 75 SbIMOi ₂ Ni ₁ Sr ₁ PiO ₄₁₁ ; 84 63 8th 76 Sb | Mo ₁₂ Sn, Sr | P | O ₄ i < 88 71 11 77 Sb] Moι iSn \ Ζ.Γ \ Ρ1Ο41> 83 60 11 78 Sb] Μθ | ιΝι | ΖΠ [P1Ο41 -ί 82 58 12th 79 Sb, MOnTa ₁ Ti ₁ P ₁ O ₄ , 96 58 16

Examples 80 to 89

In a manner similar to that in Example 60, catalysts are prepared, the atomic ratios of which are given in Table 10 are put together. The reaction according to Example 60 is repeated with these catalysts at 320 C, methacrolein is used. The results are summarized in Table 10:

Tabel 10 Catalysts Methacrolein Methacrylic acid Acetic acid- example conversion selectivity selectivity No. Sb, M0 | ₂ Nb, P | O ₄ | 88 60 8th 80 Sb ₃ MOi ₂ Nb ₃ P ₁ O ₄₆ 81 62 H 81 Sb ₅ Mo ₁₂ Sn ₁ P ₅ O ₅₀₅ 54 51 7th 82 Sb | MO | ₂ Sn | P ₅ O ₅₀₅ 21 75 2 83 Sb | Mo, ₂ Ni ₆ Fe, PiO ₄₆ 85 53 4th 84 Sb ₁ MOi ₂ TaIFe ₅ P ₁ O ₅₀ 71 54 12th 85 Sb ₃ MOi ₂ Ni ₁ SrIPiO ₄₀₅ 82 65 10 86 Sb, Mo | ₂ Sn ₃ Sr | P | O ₄₅ 85 66 15th 87 Sb ₁ Mo ₁₂ Sn ₃ Sr ₁ P ₂ O ₄₈ 75 67 13th 88 Sb | Mo ₁₂ Ni ₃ Zr, P | O ₄₃₅ 80 61 9 89

Claims (1)

Claim: Process for the production of methacrylic acid by reacting methacrolein with molecular Oxygen in the vapor phase at a temperature of 250-450 ° C in the presence of Water vapor and in the presence of an oxide catalyst containing molybdenum, phosphorus and antimony, characterized in that a catalyst of the general formula I jSb ,,, 4X0.1 where X is at least one of the elements tungsten, barium, chromium, lead, niobium, tantalum, tin, nickel, iron or zirconium and δ corresponds to the oxidation level of the elements, or the general formula II Mi) ₁₂ Pul jSn ",., X ₀₁ τ Y ₀ , -, Of ₁ where X and <5 correspond to the definition above and Y at least one of the elements strontium, Titanium, germanium, cerium or silver means uses. is characterized in that a catalyst of the general formula I